1. Field of the Invention
This invention relates to a print head device of a type in which an ink cartridge is directly mounted in a print head unit having a print head thereon, an ink jet printer incorporating the print head device, and the ink cartridge for the ink jet printer.
2. Prior Art
Conventionally, an ink cartridge for use in a print head device of the above-mentioned kind was proposed e.g. by Japanese Laid-Open Patent Publication (Kokai) No. 8-132636. The ink cartridge is comprised of a cartridge body containing ink, a delivery spout-sealing film for sealing an ink delivery spout of the cartridge body, and an air inlet passage-sealing film for sealing an ink-charging port and an air inlet passage of the same. Mounted in an inner peripheral surface of the ink delivery spout is a packing, and when the ink cartridge is mounted in a print head unit, a head needle of the print head unit pierces the delivery spout-sealing film to fit into the packing, whereby the ink cartridge is joined to the print head unit.
When this type of ink cartridge is used, the user peels off a portion (peel-off portion) of the air inlet passage-sealing film in advance to make the air inlet passage (upstream end of a meandering passage communicating with an air inlet port) open to the atmosphere, and then mounts the ink cartridge in the print head unit. As a result, the inside of the print head and that of the ink cartridge communicate with each other via the head needle, and at the same time, the inside of the ink cartridge communicates with the atmosphere, which allows ink to be delivered from the ink cartridge to the print head.
In this kind of conventional print head device, however, when the ink cartridge is mounted without peeling off the air inlet passage-sealing film (i.e. the peel-off portion thereof), the ink cannot be delivered to the print head. Further, this kind of ink cartridge is supplied in a state negatively pressurized inside. Therefore, there is an inconvenience that air can be mixed into the ink when the ink is drawn from the ink cartridge into the print head immediately before a start of printing. Once air is mixed into the ink, it is difficult to expel the air out of the ink even if the air inlet passage-sealing film is peeled off afterward, which can cause failure of printing.